A single business decision taken by one of the world’s biggest manufacturers of bed nets more than 10 years ago has exacerbated the situation.
PNG isn’t the only place where cases have soared: The World Health Organization estimates there were about 249 million infections globally in 2022, including 608,000 deaths, far exceeding levels before the Covid-19 pandemic. Faltering funding, insecticide resistance and climate change have all been propelling a continued upward trend in global malaria cases, scientists say.
Vestergaard told Bloomberg that it changed the coating primarily because a supplier discontinued production using the per- and polyfluoroalkyl substances known as PFAS, or forever chemicals. The net maker could have used a more expensive replacement when making the switch and changed other production methods to maintain effectiveness, according to two consultants with knowledge of net technology, including one former Vestergaard employee who asked not to be named.
In 2019, scientists there conducted tests on unused and unopened Vestergaard nets from villages and provincial health clinics around the country, some of which had been produced as far back as 2007. They found that nets made before 2012—the oldest ones—were all effective, while only 17 percent of those made more recently passed the test that measures the number of mosquitoes that have died or been incapacitated after exposure to net pieces.
“Cone tests are not designed to directly measure malaria transmission and the resurgence in malaria cases cannot be attributed to the performance of PermaNet 2.0 nets,” Essex said. In some African countries, the disease reduces GDP growth by about 1.3 percent a year, the World Bank estimates. While traditionally not thought of as a problem on American soil, nine homegrown malaria infections occurred in the US in 2023, the first cases in 20 years.
Other companies have also drawn criticism about the quality of their nets. In April, the WHO sent a letter of concern to Germany-based Mainpol GmbH because some of its nets contained too much or too little insecticide. In response to questions, Mainpol sent a link to a WHO inspection document at its manufacturing site in China from May that said “considering the corrective actions taken and planned,” the factory was in compliance with international standards.
“As it’s gotten more competitive, the quality has deteriorated,” Mark Rowland, professor of medical entomology at the London School of Hygiene and Tropical Medicine said about nets generally. “It’s definitely true the nets have become substandard. You can’t blame them completely because they need to make a profit.
Surging investments in combating malaria brought in new competition for manufacturers. The industry, once dominated by Vestergaard and Sumitomo, swelled with more than a dozen new entrants. Prices plunged as companies cut their costs in order to win contracts. Nets like PermaNet 2.0 that once went for nearly $5 each were available for $1.85.A breakthrough for the PNG researchers didn’t come until 2021.